Xweather Weather API

# Fix list: Xweather Weather API

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/xweather, the October 2026 research run, assessed 8 October 2026. Grade B, 67.1 out of 100.

This is everything the published grade says the listing lacks, the biggest possible gain to the total first. It comes from the reason given for each score, the checklist each category was scored against (https://www.anchorterminal.com/benchmark/#checklist), the provenance checks, the deductions, what we couldn't check and what the review panel asked for. A fix counts at the next check, once it's public.

For a coding agent working on Xweather Weather API: work through the items below in the product, its docs and its public pages. Each category gives the reason for its score, with the points each checklist item earned, and the checklist itself, so the gap is the items that earned less than their points. Change the product, not the wording, and keep a note of what you changed and where it's published.

## 1. Payments & pricing, 32 out of 100, up to 8.5 more on the total

Why it scored 32: No x402, MPP or L402 in the docs, the OpenAPI file or the pricing page (0). Plan prices are public without a login, and the cost of each endpoint in accesses is published. The overage rate is not, and the page showed us pounds only, £240 a month for 1,000,000 accesses (12 of 20). A free Developer tier of 15,000 accesses a month, with no card and no expiry per the pricing page (20). A person signs up in a browser. The MCP OAuth flow registers clients by API but still needs a human to enter the key (0).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-payments):

The published rubric, also on the [x402 page](https://www.anchorterminal.com/x402/).

- 40, a machine payment protocol (x402, MPP or L402) on the tool's own endpoints. 10 to 30 when it covers only some endpoints or only goes through a third party, and the note says which.
- 20, per-call or per-unit pricing published without a login. 10 for public plan-only pricing, 0 for "contact sales" or prices behind a login.
- 20, a free tier or trial that doesn't need a card.
- 20, autonomous onboarding, meaning an agent can get access without a person signing up in a browser (keyless use, x402, a programmatic key API).

Payment platforms and agent wallets rarely charge for their own API over a machine protocol, so the first line has steps for them, and the highest one that applies counts. 40 when x402, MPP or L402 runs on all their own endpoints, 30 when it runs on part of their own API, 25 when their merchants can accept one, 20 for running a facilitator, 15 for paying as a buyer, and 0 when the only protocol is their own. Merchant acceptance sits above a facilitator because the platform's own customers can charge agents through it, while a facilitator settles for sellers who wire up the protocol themselves. The counter-argument (a facilitator does more for the protocol as a whole) has a point. Each note says which step applied.

Open-source software you run yourself is scored on its hosted or paid option if it has one. A free, self-hosted package with nothing to buy gets 20, 20 and 20 for the last three lines, and 0 to 40 for the first only if it ships a payment protocol.

## 2. Security & auth, 52 out of 100, up to 8.4 more on the total

Why it scored 52: Credentials are a `client_id` and `client_secret` per registered app, limited to a domain or app bundle namespace and regenerated in the dashboard. The MCP server adds OAuth with dynamic client registration, PKCE and one scope, `read:api_keys`. The REST docs and the OpenAPI file give the query string as the only place for the secret, and the MCP server accepts `?api_key=` (22 less 10, 12 of 30). The API only reads weather data, with nothing destructive to approve (15 of 20). Responses are mostly numeric. Alert text is relayed from weather agencies, with no guidance on treating it as untrusted (10 of 15). Cost and quota headers come back on each call. No per-call log for the account holder was found in the docs (4 of 15). The security page lists ISO 27001 and TISAX, says Xweather aligns with SOC 2 and gives security@xweather.com, with no report linked and no bounty. xweather.com has no security.txt, while the parent vaisala.com has one with a policy link (11 of 20).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-security):

- 0 to 30, the credential model. 30 for OAuth 2.1 with scopes, or scoped and revocable keys with rotation. 20 for plain revocable API keys. 10 for one all-powerful key. 10 off when a secret can travel in a URL query string as a documented option.
- 0 to 20, read-only or least-privilege modes, and confirmation or approval for destructive actions.
- 0 to 15, prompt-injection posture where the tool returns untrusted content (documented mitigations or guidance). A tool that returns no untrusted content gets 10.
- 0 to 15, audit logs or per-call visibility for the operator.
- 0 to 20, a security programme. security.txt or a disclosure policy, a bug bounty, SOC 2 or ISO 27001, advisories handled in public.

Models are read for retention, whether API data trains models (and whether that's off by default), zero-retention options and certifications. Frameworks for telemetry defaults, approval hooks, guardrails and sandboxing.

## 3. Reliability, 74 out of 100, up to 5.2 more on the total

Why it scored 74: Graded as a hosted service. Status page at status.xweather.com on Atlassian Statuspage with 21 components, among them API General, Conditions, Forecasts, Alerts, Lightning Endpoints and MCP Server (20). It lists three incidents between 10 July and 8 October 2026. Two on 24 July are marked major and report reduced data rates from the lightning network for 33 and 72 minutes, and one on 15 July relays an upstream GOES-East satellite outage. None names the general API, conditions or forecasts components (20 of 30). Monthly quotas are published, 15,000 and 1,000,000 accesses, but the per-minute limit is given only in response headers and by support (8 of 15). 429 is documented with the codes `maxhits_min` and `maxhits`, the OpenAPI file declares `Retry-After`, seven `X-RateLimit-*` headers report the remaining allowance, the MCP docs advise exponential backoff, and failed calls are not charged. The API is read-only, so no idempotency keys are needed (13 of 15). The pricing page mentions custom SLA guarantees for enterprise plans, with no SLA document found (3 of 10). The REST API at 1.43.5 and the MCP server at 1.2.2 are generally available (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-reliability):

Hosted APIs, MCP servers, models and platforms.

- 20, a public status page with component history (Statuspage, Instatus, BetterStack or the vendor's own).
- 0 to 30, the incident record for the last 90 days on that page. 30 for a clean record or trivial incidents only, 20 for minor incidents only, 10 for one major outage (an hour or more of a core API down, or errors across the board), 0 for several. 5 when there's no history we could read, and the note says so.
- 15, rate limits documented with numbers.
- 15, documented 429 or overload handling (Retry-After, backoff guidance), and idempotency keys or safe-retry guidance where writes are involved.
- 10, an SLA published for any paid tier.
- 10, the surface agents use is generally available, not beta or preview.

Local packages, SDKs, frameworks and stdio MCP servers.

- 20, installs from an official package with supported runtimes stated.
- 25, a public CI and test suite, passing on the default branch.
- 0 to 25, open crash or regression issues relative to activity (25 for few and handled, 0 for many, old and unanswered).
- 15, semver discipline and breaking changes called out in a changelog.
- 15, version 1.0 or later, or declared stable.

Protocols are read from their reference implementations, the public facilitators or servers, spec stability and test vectors.

## 4. Agent ergonomics, 78 out of 100, up to 3.6 more on the total

Why it scored 78: `fields`, `limit` and `plimit` size a REST response, and the docs give a 15-day hourly forecast as about 600 KB, or 25 KB with three fields. The MCP server documents 19 tools, with `include_tags`, `exclude_tags`, `include_tools` and `exclude_tools` filters on the server URL (22 of 25). `limit`, `skip`, `plimit`, `pskip`, `sort`, `filter`, `query`, `from` and `to` cover paging and filtering, and `/batch` combines requests (18 of 20). Errors carry a code and description, but application errors such as `invalid_location` arrive with HTTP 200 and `success` false, so the status code alone misleads (15 of 20). All calls are reads and safe to repeat, and failed calls cost nothing. The MCP tools' annotations could not be read without a key (14 of 20). A location is the only required input and accepts a place name, coordinates or a postal code. Official SDKs are client-side, namely JavaScript (last released October 2024), iOS and Android, with Python notebooks and no server-side library (9 of 15).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-ergonomics):

- 0 to 25, context cost. For MCP, the number and size of the tool definitions (25 for ten or fewer compact tools, 15 for 11 to 30, 5 for more than 30, plus up to 10 back for toolsets, dynamic loading or read-only subsets). For APIs, whether responses can be sized (field selection, limits, summaries).
- 20, pagination, filtering and output-size controls.
- 20, actionable, documented error responses, codes and messages an agent can recover from.
- 20, idempotency or safe retries, and for MCP the `readOnlyHint` and `destructiveHint` annotations.
- 15, sensible defaults, few required parameters, and official SDKs in at least two languages.

Models are read for tool use, structured output, prompt caching, context length, batch and SDKs. Frameworks for how much code and how many defaults a tool-calling agent with MCP needs.

## 5. Schema & documentation, 83 out of 100, up to 2.8 more on the total

Why it scored 83: OpenAPI 3.2.0 and 3.1.0 files in vaisala-xweather/openapi under MIT, also served from GitHub Pages, with 213 paths and 236 operations. They were first published on 30 September 2026. The MCP tools' input schemas need a key to list and were not read (25). llms.txt at www.xweather.com/llms.txt indexes the site and docs pages. The docs pages have no Markdown copies (a .md address returns 404), though six agent skills in Markdown cover request building (8 of 10). Every operation and parameter in the OpenAPI file has a description, and the MCP tool pages state each tool's purpose and limits, such as a 24-hour tool marked as not for multi-day forecasts (16 of 20). The file has 9 enums and 10 required parameters among 2,289 parameter uses, and `filter`, `query` and `sort` are free strings with their own grammar (8 of 15). Each operation declares 200, 401, 404, 429 and 500 with examples, and the docs list 16 error codes and the warning codes (13 of 15). Dated, numbered changelogs for the API and the MCP server. The API path carries no version (13 of 15).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-schema):

APIs and MCP servers.

- 25, a machine-readable contract (a public OpenAPI file or similar; for MCP, typed JSON Schema inputs on every tool).
- 10, llms.txt or Markdown docs served for agents.
- 0 to 20, descriptions that say what a tool is for, when to use it and when not to, read from the tool definitions in the source or the API reference.
- 0 to 15, typed inputs with enums, constraints and required fields, and no free-form JSON blobs.
- 0 to 15, examples and documented error responses.
- 15, versioning and a public changelog.

Models are read from the API reference, the OpenAPI file, llms.txt, the structured-output and tool-use docs and the model cards. Frameworks from docs a model can follow, typed interfaces, examples and the API reference.

## 6. Transparency & trust, 68 out of 100, up to 2.8 more on the total

Made of editorial 51, provenance 85.

Why it scored 68: Closed service under Vaisala's group subscription terms, dated 1 January 2023, which set a liability cap of twelve months' fees and ICC arbitration. They are written for annual, invoiced contracts and leave the product's own rules to service descriptions that were not found in public. The OpenAPI files and agent skills are MIT (15 of 30). The privacy policy is the group policy effective 1 June 2020. It covers online services, keeps data for a period it calls reasonable with no figure, and still cites the US Privacy Shield. No DPA was found (12 of 30). The changelog marks deprecations with dates, the API has `deprecated` and `warn_deprecated` codes, and the terms promise notice of modifications with a 30-day right to end the contract after a material reduction. No notice period is stated (8 of 20). A data processors page names about 40 processors with a location for each, with a caveat that it may be incomplete (16 of 20).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-transparency):

- 0 to 30, source availability and licence clarity. 30 for open source under an OSI licence, 15 for closed with clear terms, 0 for unclear terms.
- 0 to 30, data handling and retention statements that agree with each other (privacy policy, DPA, retention periods, subprocessors).
- 0 to 20, a deprecation policy or notices with dates.
- 0 to 20, telemetry disclosed with an opt-out (local software), or subprocessors and data locations disclosed (hosted).

The other half of Transparency and trust is the provenance score, computed from checked facts (below). The category score is the mean of the two.

Provenance checks not met in full (half of this category, computed from checked facts):

- Terms of service: published, but our reader couldn't read it (7 of 10)
- Privacy policy: read, states 5 of the 8 things a reader expects (7.8 of 10)
- security.txt: not found (0 of 10)

## 7. Maintenance & community, 81 out of 100, up to 1.7 more on the total

Why it scored 81: The newest API release is 1.43.5 on 14 September 2026, 24 days before this check (30). Three API releases fall in the last 90 days, 1.43.3 on 29 July, 1.43.4 on 31 August and 1.43.5 on 14 September, and the agent skills repository had releases 0.14.1 to 0.15.1 between 1 September and 5 October (20). Public changelogs, a ticket form and support@xweather.com, with community support on the free tier and priority email on the paid plan. Response times were not tested (10 of 15). The MCP server is in the official registry as com.xweather/weather, active since 2 September 2026 (15). The JavaScript SDK `@aerisweather/javascript-sdk` was last released in October 2024, while the OpenAPI and skills repositories carry CI and recent commits (6 of 10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-maintenance):

- 0 to 30, time since the last release, or the last published model or API change for a closed service. 30 within 30 days, 20 within 90, 10 within 180, 0 older.
- 20, at least three releases or dated changelog entries in the last 90 days.
- 0 to 25, responsiveness. Issues and pull requests answered on GitHub (the open issues and how recent the replies are). For closed services, a public changelog and a support or community channel that answers, 0 to 15.
- 15, presence in the official MCP registry under a verified namespace (MCP servers), or current official SDKs (APIs and models).
- 10, package health, current dependencies and CI.

Models are read for deprecation notice periods and model churn rather than release counts.

## What we couldn't check

What we couldn't read counted as absent. Publishing it on a page a plain HTTP fetch can read (not only in a browser) lets the next check count it.

- unchecked: the US dollar plan price. The US and Canada pricing page redirected us to the international page, which showed £240 a month, so unitPrices is empty
- unchecked: the overage rate beyond 1,000,000 accesses, which the pricing page does not state
- unchecked: the MCP tools' input schemas and annotations, which need a key to list. The count of 19 is from the docs pages
- unchecked: whether the free Developer tier includes MCP access. The docs say a 403 means the subscription lacks it
- unchecked: per-minute rate limits by plan. The docs give headers and refer callers to support
- unchecked: whether signup asks for a card. The pricing page says none is required for the Developer tier, and we did not open the checkout
- Whether a Weather API service description permits commercial use or redistribution. The group terms prohibit commercial use of freemiums and bar passing data to third parties unless a service description allows it, and no such description was found in public
- Which Vaisala company contracts for Xweather. The terms say the company named on the quotation or invoice, and the privacy policy names Vaisala Oyj, which we used as the legal entity
- The security page says Xweather maintains ISO 27001 practices and aligns with SOC 2. No certificate or report was linked, so the scope is unknown
- The docs' authentication page calls the scheme OAuth 2.0, but REST calls send a static ID and secret in the query string
- The lead was right about the MCP server, agent skills and SDKs. The SDKs are client-side (JavaScript, iOS, Android), and the docs link the old status address status.aerisweather.com, which redirects to status.xweather.com

## Weaknesses

- The REST API documents `client_id` and `client_secret` only as query parameters, and the MCP server also accepts the key as `?api_key=`
- Per-minute rate limits are not published. The docs refer callers to response headers, support or an account executive
- The group subscription terms prohibit commercial use of freemium plans and bar making data available to third parties unless a service description allows it
- One access is not one request. `/impacts` costs 25 accesses, `/lightning` 10 and air quality 5, multiplied by the time intervals requested
- No overage price or US dollar price was readable. The pricing page served us pounds, £240 a month for 1,000,000 accesses
- The privacy policy is Vaisala's group policy effective 1 June 2020, with no retention period stated and no DPA found

## What costs an agent a turn today

The notes we give agents before they call it. Each one is a workaround an agent shouldn't need.

- Check `success` and `error.code` on every response. Application errors such as `invalid_location` return HTTP 200 with `success` false
- Send `fields`, `limit` and `plimit`. The docs put a 15-day hourly forecast at about 600 KB, and about 25 KB with three fields
- Read `X-Cost-Tokens` after each call. Cost is the endpoint multiplier times the intervals requested, so narrow `from` and `to`
- For MCP, send `Authorization: Bearer <client_id>_<client_secret>` and avoid the `api_key` query parameter, which puts the secret in the URL
- Add `include_tags` or `include_tools` to the MCP URL to load only the tool groups the task needs
- On 429 read `Retry-After` and the `X-RateLimit-Reset-*` headers. `maxhits_min` clears at the next minute, `maxhits` at the period reset

## When it's done

Send what changed and where it's published as a dispute (https://www.anchorterminal.com/builders/#disputes, or `POST https://www.anchorterminal.com/api/v1/contact` with `"kind": "dispute"`). Disputes are answered in public, and the listing is checked again by the same checklist. Paying for an audit or a listing claim changes nothing here.